The present invention relates to an apparatus for controlling a sewing machine to stitch a prescribed pattern by successively reading out pattern data written in a semiconductor memory device.
One prior apparatus of the type described above is shown in FIG. 1 of the accompanying drawings. The apparatus includes a control circuit 1 in the form of an eight-bit microcomputer, for example, and a semiconductor memory device 2 in which pattern data has been written. Sixteen address lines 3 which convey addresses for specifying data storage locations in the semiconductor memory device 2. The semiconductor memory device 2 is physically arranged such that it can easily be replaced with other memory devices having different pattern data stored therein. The apparatus also includes eight data lines 4 for delivering data stored at an address specified by the address lines 3 to the control circuit 1, and control signal lines 5 for delivering a control signal from the control circuit 1 to the semiconductor memory device 2.
The operation of the conventional control apparatus shown in FIG. 1 is as follows: During a cycle in which the control circuit 1 reads data, the control circuit 1 issues signals necessary for reading the data from the semiconductor memory device 2 over the control signal lines 5 (indicated by C0-C3), and the semiconductor memory device 2 is in readiness for sending out the data over the data lines 4. At this time, the 16 address lines 3 (designated by A0-A15) deliver a first address signal of "0000 0000 0000 0000" to address a head address in the semiconductor memory device 2. The data stored in the head address is then delivered over the data lines 4 (indicated by D0-D7) and read by the control circuit 1. Address signals are then successively delivered over the address lines 3, and data stored at the addresses specified by such successive address signals is delivered sequentially from the semiconductor memory device 2 over the data lines 4 (D0-D7) and read by the control circuit 1.
When the control circuit 1 reads pattern data for sewing, for example, stored in the semiconductor memory device 2, the control circuit 1 controls various parts of an electronic sewing machine for stitching a predetermined pattern based on the pattern data the control circuit 1 has read. Since the semiconductor memory device 2 with data written therein is replaceable, it may be replaced by another data storage semiconductor memory device to sew a different pattern.
The conventional electronic sewing machine control apparatus of the foregoing construction can effect sewing with various different sewing patterns simply by changing semiconductor memory devices. There are a wide variety of semiconductor memory devices presently available, and the trend is toward the development of larger-capacity, less costly devices. However, the prior control apparatus of the type described above can be used with only one type of semiconductor memory device available at present, and thus is poor in compatibility.